IDM MAG-2E1 Digital Trunk Gateway

The IDM MAG-2E1 digital trunk gateway is a 1U rack-mounted E1 digital trunk gateway developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. (Raytrans). As an IP access gateway, it performs call protocol conversion and media stream intercommunication between the IMS/SIP softswitch side and the ISDN PRI trunk of an existing SPC exchange (PBX). The IDM MAG-2E1 E1 digital trunk gateway provides 1 to 4 E1/T1 interfaces, 512 SIP trunk account registrations, and up to 120 concurrent calls at full configuration. Through 4 10/100/1000 Base-T adaptive network ports, it connects to a SIP softswitch, IMS platform, or IP-PBX, integrating traditional trunk telephone services and IP voice services into a single communication network. The device supports dual network ports, dual power supply redundancy, and -36 to -72V DC power supply. Its 1U rack-mounted structure carries service aggregation in electric power/energy, rail transit, military/government, and other industrial private network equipment rooms through high-density trunk access, meeting the IP voice access requirements of medium and large industrial private networks.

Key specifications at a glance: 4 E1/T1 ports · 512 SIP trunks · 120 concurrent calls at full configuration · SIP/UDP and SIP/TCP · ISDN PRI (30 B+D) and T1 23B+D · dual network ports and dual power supply redundancy · -36 to -72V DC · 1U rack-mounted · overall power consumption 18W

Figure 1: Close-up of the E1/T1 interfaces and indicator LEDs on the front panel of the IDM MAG-2E1 digital trunk gateway

What kind of device is the IDM MAG-2E1 E1 digital trunk gateway?

An E1 digital trunk gateway is a protocol conversion and media processing device located between the trunk side of a PSTN or SPC exchange and an IP voice network. One side connects to an E1/T1 PRI trunk, and the other side registers with a softswitch, IMS platform, or IP-PBX over SIP. The IDM MAG-2E1 digital trunk gateway converts call protocols between IMS/SIP and ISDN PRI (30 B+D) through its network ports and E1/T1 interfaces. It is used for connecting a new-generation IP voice service network with an enterprise-side traditional SPC exchange (PBX), and also for connecting an enterprise IP voice switch (IP-PBX) to a traditional PSTN network. It is a typical trunk access device in the IP access gateway product showcase.

The IDM MAG-2E1 E1 digital trunk gateway has an overall processing capacity of 6000MIPS and can still perform voice processing (G.711/G.729A/G.723.1), echo cancellation, and T.38 fax relay at 120 concurrent calls. A single 1U device can handle the trunk access and aggregation of a medium-sized private network. The device adopts a 44×440×300mm 1U rack-mounted structure. Its physical interfaces include 4 E1/T1 interfaces, 4 gigabit adaptive RJ45 network ports, 1 SD card interface, and 1 RJ45 configuration port (CON). It has 512MB of system memory and 64MB of flash memory.

The trunk side and IP side of the E1 digital trunk gateway are independent of one another in terms of alarms and maintenance: the IDM MAG-2E1 E1 digital trunk gateway provides bit error rate (BER) tests, local loopback, and B/D channel status queries for ISDN links. Trunk failures can be located at the link, time slot, and call levels without segment-by-segment troubleshooting using external instruments.

Which call control protocols and voice codecs does this trunk gateway support?

The call control of the IDM MAG-2E1 E1 digital trunk gateway supports both SIP/UDP and SIP/TCP bearer modes, as well as IMS platform interconnection based on 3GPP specifications. Voice encoding and decoding covers five algorithms: G.711, G.729A, G.723.1, GSM, and iLBC. The table below summarizes the protocol and media processing capabilities. During selection, determine the codec combination according to the peer softswitch platform type and link bandwidth conditions.

Item	Protocol/Algorithm	Description
Call control	SIP/UDP, SIP/TCP (RFC3261), IMS platform (3GPP)	Interconnects with SIP softswitch and IMS platform
Network protocols	Telnet, SSH, HTTP, HTTPS, DHCP client, PPPoE client, DNS, STUN	Supports PPPoE dialing and registration in NAT environments
Voice encoding and decoding	G.711, G.729A, G.723.1, GSM, iLBC	Selected according to bandwidth and voice quality requirements
Fax	G.711 transparent transmission fax, T.38 fax, compatible with G3 fax machines, transparent transmission rate up to 33.6kbps	T.38 is recommended when fax traffic is heavy
Voice quality enhancement	Echo cancellation (G.168-2004), jitter buffer, silence suppression (VAD/CNG), PLC	Suppresses echo and packet loss effects in long-distance calls
Media proxy	Media stream RTP packet forwarding, firewall traversal, NAT traversal	Media streams do not pass through third-party relays
Signaling	E1 ISDN PRI (30 B+D), T1 ISDN PRI (23 B+D, ANSI NI-2)	Switch types compatible with 5ESS series and DMS series
DTMF	In-band voice transmission, RFC2833, SIP-INFO	Supports secondary dialing by attendant console and IVR
QoS	DiffServ, TOS, 802.1P/Q VLAN	Voice VLAN and priority marking

The interface characteristics of the E1 trunk side follow ITU-T G.703/G.704 recommendations. A single E1 link has a rate of 2.048Mbps and uses HDB3 line encoding. The D-channel signaling of ISDN PRI follows ITU-T Q.921/Q.931 recommendations. In E1 format, it is 30 B channels plus 1 D channel (30 B+D); in T1 format, it is 23B+D.

What core functions does this trunk gateway have?

The functions of the IDM MAG-2E1 E1 digital trunk gateway can be divided into five categories: trunk access, voice processing, registration and routing, security protection, and O&M management. All five categories are enabled simultaneously within the same 1U device, without the need for external trunk boards or a protocol conversion server. The function items and their purposes are shown in the table below.

Function	Description
Trunk access	Provides 1 to 4 E1/T1 interfaces, supports E1 ISDN PRI (30 B+D, Chinese standard) and T1 ISDN PRI (23 B+D, ANSI NI-2 North American standard); switch types compatible with 5ESS series and DMS series
Call control	Supports SIP/UDP, SIP/TCP (RFC3261), and IMS platform (3GPP); performs call protocol conversion between IMS/SIP and ISDN PRI
Voice encoding and decoding	Supports G.711, G.729A, G.723.1, GSM, and iLBC; codecs can be negotiated according to peer capabilities
Fax processing	Supports G.711 transparent transmission fax and T.38 fax, compatible with G3 fax machines, transparent transmission rate up to 33.6kbps
Voice quality enhancement	Echo cancellation (G.168-2004), jitter buffer, silence suppression (VAD/CNG), PLC packet loss compensation
Media proxy	Media stream RTP packet forwarding, firewall traversal, NAT traversal
Registration and authentication	Supports gateway registration and authentication, 512 SIP trunk account registrations
Number and routing	Number conversion, call routing (500 entries), number bitmap, RADIUS billing interface
QoS guarantee	DiffServ, TOS, 802.1P/Q VLAN marking
Security protection	HTTPS, SSH, TLS, SRTP; SIP signaling encryption and media stream encryption; encrypted configuration file import/export, password encryption; access whitelist, Ping disabled, SIP trusted address
Port customization	SIP port, HTTP/HTTPS access port, and RTP port can be customized
Redundancy protection	Dual network port and dual power supply redundancy protection; disaster recovery mechanism for active/standby SIP server switchover
Automatic management	Supports file download via TFTP, FTP, HTTP, or HTTPS; obtains ACS address via DHCP option 66 or redirection
Maintenance and diagnostics	8-level log management, Syslog; port voice capture and packet capture; call status and statistics, system status, ISDN status queries
ISDN maintenance	Bit error rate (BER) test, local loopback, and B/D channel status queries for ISDN links
Version upgrade	Upgrade via the device Web interface, or batch upgrade via the remote automatic management system
Matching tool	Finder software is used to find the device IP address within a local area network (LAN)

Key specifications: 4 E1/T1 interfaces, concurrent calls, and power supply mode

The interface and operating parameters of the IDM MAG-2E1 E1 digital trunk gateway are subject to the product documentation. The table below summarizes hardware interfaces, processing capacity, power supply, and environmental specifications for selection and equipment room conditions verification. The upper limit of concurrent calls is determined by the number and format of E1/T1 interfaces, and the power supply mode must be determined according to whether the site is an AC or DC equipment room.

Item	Parameter/Specification	Description/Applicable Conditions
Network ports	RJ45, 4×10/100/1000 Base-T, adaptive	Used to connect to softswitch, IMS platform, and network management
T1/E1 interfaces	4 (120 concurrent calls at full configuration)	E1 format 30 B+D; upper limit of concurrent calls at full configuration is 120
SD card interface	1	For local file storage
CON configuration interface	RJ45	Local configuration and maintenance
System memory	512MB	—
Flash memory	64MB	—
Processing capacity	6000MIPS	Still performs voice processing, echo cancellation, and fax relay at 120 concurrent calls
Physical dimensions	H×W×D (1U): 44×440×300mm	Rack-mounted installation
Net weight	Within 3kg	—
Single/dual AC power supply	100 to 240 volts, 50/60 hertz, within 1 ampere	Single or dual power supply selectable for AC equipment rooms
Single/dual DC power supply	-36 to -72 volts, within 2.5 amperes	Covers -48V nominal DC, suitable for equipment rooms powered by DC distribution panels
Overall power consumption	18W	Overall power consumption at full configuration with concurrent calls
Installation method	Rack-mounted	1U standard cabinet installation
Operating environment	Temperature 0 to 40℃; relative humidity 10% to 90% (non-condensing)	Equipment room and station building environments
Storage environment	Temperature -40 to 70℃; relative humidity 5% to 90% (non-condensing)	Transportation and storage conditions
Lightning protection	3.5kV	Outside line side protection

How does ISDN PRI trunk access interconnect with an existing SPC exchange?

The key to ISDN PRI trunk access lies in matching the trunk format, signaling type, and peer switch model. As an IP access gateway designed for private network scenarios, the PSTN access side of the IDM MAG-2E1 E1 digital trunk gateway supports both E1 ISDN PRI (30 B+D, Chinese standard) and T1 ISDN PRI (23 B+D, ANSI NI-2 North American standard), and its switch types are compatible with 5ESS series and DMS series. It can therefore adapt to the existing SPC exchanges of industry users. Before access, the trunk format, signaling type, and time slot occupation mode must be checked item by item with the peer end.

When an E1 digital trunk gateway interconnects with an SPC exchange, the physical layer operates according to ITU-T G.703/G.704, with a single-link rate of 2.048 Mbps and HDB3 line encoding; at the signaling layer, the D channel follows ITU-T Q.921/Q.931. Number and routing processing is performed on the device side, supporting number conversion, call routing (500 entries), and number bitmap, and call detail records can be sent to the billing system through the RADIUS billing interface. In upgrade projects, the number plan of the existing SPC exchange does not need to be readjusted. This capability also enables the device, in IP-PBX and PSTN trunk interconnection solutions, to act as an ISDN PRI protocol conversion gateway and achieve smooth interconnection between traditional trunks and the IP voice network.

In-band signaling and fax require separate confirmation of the encoding method. The DTMF of the IDM MAG-2E1 E1 digital trunk gateway supports three modes: in-band voice transmission, RFC2833, and SIP-INFO, which are selected according to the capabilities supported by the opposite end when interfacing with an attendant console, IVR, or secondary dialing services; fax supports G.711 transparent transmission fax and T.38 fax, is compatible with G3 fax machines, and supports transparent transmission rates up to 33.6 kbps. When link jitter is significant, switching to T.38 can reduce fax failures.

Why Does a Private Network Trunk Access Gateway Need Dual Power Supplies and DC Power Supply?

The availability of a private network trunk access gateway directly determines whether trunk telephone services can continue. The IDM MAG-2E1 E1 digital trunk gateway implements redundancy design at three levels: power supply, network, and registration. On the power supply side, it supports single/dual AC power supply or single/dual DC power supply, and can be configured with 1+1 power supply modules; on the network side, it provides dual network port redundancy protection, so a local network failure does not affect calls; on the registration side, it provides a disaster recovery mechanism for active/standby SIP server switchover, so trunk services switch to the standby server when the primary server fails. The three levels of redundancy together support continuous operation under unattended conditions in a private network equipment room.

DC power supply is a practical constraint in equipment rooms of industries such as electric power and rail transit. In an equipment room with centralized power supply from a DC distribution panel, a DC-powered trunk gateway can draw power directly from the -48V DC system, eliminating the AC inverter stage; the IDM MAG-2E1 E1 digital trunk gateway supports -36 to -72V DC input (within 2.5 amperes), and the input range covers the -48V nominal voltage. For AC equipment rooms, the 100 to 240V AC power supply version is selected. Both power supply versions support single and dual power supply configurations.

Low power consumption and a wide storage temperature range reduce equipment room requirements. The IDM MAG-2E1 E1 digital trunk gateway has an overall power consumption of 18W, occupies no additional cabinet space with 1U rack installation, operates at 0 to 40°C and is stored at -40 to 70°C, and provides 3.5kV lightning protection, so it can be deployed directly in a communications equipment room or a station building along the line.

Differentiated Value: 512 SIP Trunks, 4 E1/T1 Ports, and Dual Power Supply Redundancy

The differentiated value of the IDM MAG-2E1 E1 digital trunk gateway is concentrated in four aspects: 512 SIP trunk and 4 E1/T1 trunk access, full-load voice processing capacity, redundancy and unattended adaptation, and dual-format trunk interfacing. The values and corresponding capabilities are shown in the table below. The parameters in the table are compiled from product documentation; for specific configurations, please confirm with the manufacturer based on project requirements.

Selling Point	Corresponding Capability	Customer Value
512 SIP trunk account registrations and 4 E1/T1 interfaces	Supports 1 to 4 E1/T1 interfaces and simultaneously supports 512 SIP trunk account registrations	Trunk telephone and SIP account access for medium and large industrial private networks is centralized in one 1U device, eliminating the need for multiple gateways
6000 MIPS processing capacity and guaranteed G.711 voice processing at 120 concurrent calls at full configuration	6000 MIPS processing capacity for the unit; at 120 concurrent calls at full configuration in E1 format, it still performs G.711/G.729A/G.723.1 voice processing, echo cancellation, and T.38 fax relay	Voice quality does not degrade under full-load calls, and no additional processing resources need to be reserved for peak traffic
Dual network ports, dual power supply redundancy, and active/standby SIP switchover	Dual network port redundancy protection, single/dual power supply configuration and 1+1 power supply modules, active/standby SIP server switchover	Trunk services are uninterrupted during a single point of failure in power supply, network, or softswitch server, supporting continuous operation of unattended equipment rooms in industrial private networks
Dual format of E1 ISDN PRI (30 B+D) and T1 ISDN PRI (23 B+D)	The PSTN access side is compatible with Chinese standards and the ANSI NI-2 North American standard; switch types are compatible with the 5ESS series and DMS series	Adapts to the existing SPC exchanges of industry users, so trunk upgrades do not require replacing the opposite-end equipment

Typical Application Scenarios

The typical networking approach of the IDM MAG-2E1 E1 digital trunk gateway is to connect the E1/T1 links on the trunk side to the PSTN or an existing SPC exchange, and connect the network ports on the IP side to the local area network where the softswitch, IMS platform, or dispatch system resides, so that trunk telephone and IP voice services intercommunicate on the same network. The following three types of private network scenarios have concentrated requirements for trunk access reliability, power supply mode, and security protection.

Electric Power and Energy Private Networks: Trunk Aggregation in DC Equipment Rooms

Power dispatch telephones and plant and substation administrative telephones are mostly carried by SPC exchanges, and equipment room power is usually provided centrally by a -48V DC distribution panel. The IDM MAG-2E1 E1 digital trunk gateway connects directly to the existing DC power system with -36 to -72V DC input, aggregates PRI trunks from dispersed sites to the dispatch softswitch side through 4 E1/T1 interfaces, and covers the trunk traffic of a regional private network with 120 concurrent calls at full configuration; 1U rack installation facilitates capacity expansion in an existing communications cabinet. An unattended substation communications equipment room can deploy it on the spot, and trunk services continue to run with the station DC system.

Rail Transit Private Networks: Trunk Access for Station and Section Telephones

Official telephones and section telephones in rail transit and railways need to be connected from station exchanges to the line communication network. The IDM MAG-2E1 E1 digital trunk gateway interconnects with existing transmission and switching equipment according to ITU-T G.703/G.704, converts E1 PRI trunks to SIP signaling for access to the line softswitch, and handles station power supply and network fluctuations with dual network ports and dual power supply configuration; bit error rate (BER) tests and local loopback queries on ISDN links can locate trunk degradation without affecting calls.

Military and Government Private Networks: Encrypted Trunks and Centralized Network Management

Military and government private networks have high requirements for the security and manageability of trunk access. The IDM MAG-2E1 E1 digital trunk gateway supports HTTPS, SSH, TLS, and SRTP protocols as well as SIP signaling encryption and media stream encryption, and works with access whitelist, Ping disabled, and trusted address to prevent malicious intrusion; the device supports remote management through the network management system, automatically downloads configuration files through TFTP, FTP, HTTP, or HTTPS, and can also obtain the ACS address through DHCP option 66 or redirection for bulk provisioning. Port voice capture and packet capture provide a basis for post-event tracing.

Summary

The IDM MAG-2E1 E1 digital trunk gateway concentrates 4 E1/T1 trunk access, 512 SIP trunk account registrations, 120 concurrent calls at full configuration, and SIP/IMS interfacing in a 1U rack, forms redundancy with dual network ports, dual power supply redundancy, and active/standby SIP server switchover, and adapts to the DC equipment rooms of electric power and rail transit with -36 to -72V DC power supply. For electric power, rail transit, and military and government private network users who are migrating trunk telephone services to the IP voice network while needing to retain existing E1/T1 trunks, the IDM MAG-2E1 can be incorporated into the overall communication plan as a trunk access and aggregation node. For specific link quantities, power supply versions, and signaling types, please confirm with the manufacturer based on on-site conditions.